# [Pw_forum] A method on defining a based-centered monoclinic cell

liu hanyu ouuing at gmail.com
Mon Mar 9 09:05:06 CET 2009

```The solution is very excellent.

On Sat, Mar 7, 2009 at 11:14 AM, yinwei_li <yinwei_li at yahoo.cn> wrote:
> Dear Pwscf users,
>
>     Recently I found an effective way on input defining a based-centered
> monoclinic cell.
>
> In fact, we could  change the setting (ibrav=13) in the flib/latgen.f90 from
>      sen = sqrt( 1.d0 - celldm(4) ** 2 )
>      a1(1) = 0.5 * celldm(1)
>      a1(3) =-a1(1) * celldm(3)
>      a2(1) = celldm(1) * celldm(2) * celldm(4)
>      a2(2) = celldm(1) * celldm(2) * sen
>      a3(1) = a1(1)
>      a3(3) =-a1(3)
>
> to
>
>      sen = sqrt( 1.d0 - celldm(4) ** 2 )
>      a1(2) = 0.5 * celldm(1)
>      a1(3) =-0.5 * celldm(2) * celldm(1)
>      a2(2) = 0.5 * celldm(1)
>      a2(3) = 0.5 * celldm(2) * celldm(1)
>      a3(1) = celldm(3) * sen * celldm(1)
>      a3(2) = celldm(3) * celldm(4) * celldm(1)
>
> which corresponding with the defining form in the MS.
>
> I have tested it and found this way of defining could give us a right
> structure.
>
> For some stuctures which have problems in input defining the cell, I think
> we could resolve it in the same way
> "change the defining form in latgen.f90 to a new one which corresponding
> with that in the MS"
>
> Good Luck!
>
> Yinwei Li2009-
>
>
> Y03-07 body centered tetragonal
> ________________________________
>      sen = sqrt( 1.d0 - celldm(4) ** 2 )
>      a1(1) = 0.5 * celldm(1)
>      a1(3) =-a1(1) * celldm(3)
>      a2(1) = celldm(1) * celldm(2) * celldm(4)
>      a2(2) = celldm(1) * celldm(2) * sen
>      a3(1) = a1(1)
>      a3(3) =-a1(3)
> yinwei_li
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>

--
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Hanyu Liu, Master Student
State Key Laboratory of Superhard Materials, Jilin University, China
Email: ouuing at email.jlu.edu.cn | ouuing at gmail.com

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